Formation of monomineralic Fe-Ti oxide ores in the high-Ti ferrobasaltic system: A case study in Emeishan, China

层状侵入体中的岩浆铁矿是工业生产中铁、钛、钒等金属的主要来源之一。Fe-Ti-V氧化物富集层的起源仍然知之甚少，可能涉及不同的过程，这取决于自然案例研究。在这项研究中，我们将联合收割机结合自然样品的地球化学研究（由北京的中国合作伙伴负责）和实验方法（由德国合作伙伴负责），以了解中国峨眉山大火成岩省（ELIP）的近单矿物磁铁矿层的形成。这样的单矿物矿床是罕见的，在峨眉山省的情况下，地球化学和自然观测表明，熔体的不可渗透性在矿石的形成过程中并不起主要作用。 该研究计划旨在了解ELIP磁铁矿层的形成，并将解决以下问题：-哪些因素对最原始的高钛铁玄武岩演化过程中的Fe-Ti氧化物的稳定性产生主要控制作用，以及岩浆分异过程中最富Fe-Ti的熔体成分是什么？- 玄武岩浆和灰岩（作为寄主岩石）之间的相互作用在多大程度上影响岩浆分异和含铁、钛矿物的结晶行为？岩浆的补充作用，即演化岩浆与原始岩浆的混合作用，在多大程度上增加了Fe-Ti-氧化物的稳定场，或影响了Fe-Ti-氧化物作为唯一稳定固相的条件？岩石和矿物（常量和微量元素）地球化学特征与高压实验结果的互补性，将为峨眉山层状侵入体岩浆演化历史提供定量的制约。

Magmatic iron ore from layered intrusions is one of the major sources for Fe, Ti and V metals used in industrial processes. The origin of the Fe-Ti-V oxide-rich layers is still poorly understood and may involve different processes, depending on the natural case studies. In this study we will combine the geochemical study of natural samples (under the responsibility of Chinese partners of Beijing) and an experimental approach (under the responsibility of the German partners) to understand the formation of the nearly monomineralic magnetite layers in the Emeishan Large igneous Province (ELIP), China. Such monomineralic deposits are uncommon and, in the case of the Emeishan Province, geochemical and natural observations indicate that melt immiscibility does not play a major role during the formation of the ores. The research program aims at understanding the formation of magnetite-layers from ELIP and will tackle the following questions:- Which factors do exert a major control on the stability of Fe-Ti oxides during the evolution of the most primitive high-Ti ferrobasalt and what is the most Fe-Ti-rich melt composition during magma differentiation? - To which extent can interaction between basaltic magmas and limestone (occurring as host-rock) affect magma differentiation and the crystallization behavior of Fe- and Ti-bearing minerals?- To which extent can magma replenishment, i.e. mixing between evolved and primitive magmas, increase the stability field of Fe-Ti-oxides or affect the conditions at which Fe-Ti-oxides are the only stable solid phases?The complementarity of the geochemical characterization of rocks and minerals (major and trace elements) and of the constraints gained from high pressure experiments will provide quantitative constraints on the magma evolution history in the layered intrusions of Emeishan province.